Mullally also is climbing aboard the second season of another Fox show. She plays the new boss of Contra Security as "Breaking In" resumes Tuesday, March 6, with the humor more office-based as she joins continuing cast members including Christian Slater, Bret Harrison and Odette Annable (who also is doing extra Fox duty as she films the final episodes of "House," which will be back in April).

"I remembered seeing the billboards, but I hadn't seen the show," the spirited Mullally recalls of receiving the "Breaking In" offer. "They sent me three episodes, and I thought, 'This definitely has potential.' I got on the phone with the producers, and they were very nice, and we talked about what qualities might play best for my character. Then they wrote two sample scenes, and I thought this was something I could have a good time with."

Though Michael Rosenbaum ("Smallville") has left "Breaking In," Mullally is enjoying working with another newcomer to the show: Welsh actress Erin Richards, who plays the new chief's executive assistant.

Joining an existing series isn't new for Mullally, who did the same on the Starz comedy "Party Down" after Jane Lynch left to begin her "Glee" run on Fox.

"I would say the difference is that on 'Party Down,' they didn't miss a beat," Mullally notes. "They just plugged me in and carried on exactly the same as before. 'Breaking In' has been completely revamped, and it's almost like starting from scratch."

The fact that Slater's character is no longer the boss alters "Breaking In" automatically. "Christian has so much energy, just a bottomless well of it, physically and emotionally," Mullally says. "And it's positive energy, which is great.

"Since he's No. 1 on the call sheet, that's always a nice thing, and he couldn't have been nicer in welcoming me. He sent me a lovely email when I decided to do the show, and he sent flowers on my birthday. He really is quite a gentleman, and we have good chemistry, which is helpful."

Though spouse Offerman is busy with his own series role as Ron Swanson, who has become iconic among "Parks and Recreation" fans, Mullally hopes he might have enough time to do a "Breaking In" guest shot before the season ends.

"I would love that," she says. "We've done an inordinate amount of things together recently, including three movies; one of them, 'Smashed,' was just shown at the Sundance Film Festival. I think that with every project I do, they're secretly hoping they can get Nick. And I don't want to flatter myself, but it also might hold true the other way around."